Six Mile Creek-Halsted Bay Habitat Restoration Phase I
The Six Mile Creek Halsted Bay (SMCHB) Habitat Restoration program restored 2,488 acres of deep and shallow lake habitat by implementing the state's most ambitious program to manage common carp below the threshold where they damage lake ecosystems with three primary tactics:
- Installation of utilities to operate aeration at three locations to limit carp reproduction.
- Construction of four carp barriers to impede carp migration.
- Removal of approximately 30,325 carp totaling 284,119 pounds, resulting in the majority of waterbodies meeting or near the 100 kg/ha carp biomass goal.
The program took a comprehensive approach to managing common carp in the SMCHB Subwatershed to reach the 100 kg/ha carp biomass threshold for each waterbody.
This approach consisted of three management strategies:
-Adult biomass removal:
- Over the past five years, the District deployed a variety of tactics to remove carp across the SMCHB Subwatershed. These methods included stream trapping at barriers, baited box net trapping, and commercial winter seining.
-Barriers to prevent carp movement:
- Barrier locations were determined by a University of Minnesota Study to block critical movement pathways between lakes and impede carp migration between Lake Minnetonka and the SMCHB subwatershed. The barriers were designed to be durable and minimally impact the stream channel to prevent erosion. They were also designed to be raised and lowered to allow for easy cleaning and to facilitate native fish passage at times when carp migration is not occurring.
-Aeration of shallow lakes to prevent carp reproduction:
- Surface water aeration was implemented in high-risk carp recruitment areas. Aeration prevents winterkill of the native bluegill sunfish, a predator of carp eggs. Feasibility of each site included consideration of the closest utility connection, reasonable ability to access, and best location for operating aerators near the deepest point on the lake.
-Adaptive Management and Effectiveness Monitoring:
- Throughout the implementation of the SMCHB Habitat Restoration Program, the District deployed an adaptive management strategy that utilized a variety of monitoring approaches and evaluation techniques. These actions included quantifying biomass removal relative to original carp removal targets for each lake, monitoring surveys that update carp population estimates with boat electrofishing, and documenting in-lake habitat response as carp densities were reduced through aquatic vegetation surveys and water quality sampling. These actions have enabled us to refine our system understanding, minimize uncertainty and risks by removing carp, track ecosystem responses to reduced carp densities, and guide the development of a long-term monitoring and maintenance plan that will sustain program achievements beyond the LSOHC funding period. As MCWD continues to analyze data from the program, it will document insights and formulate recommendations to further the collective understanding of where targeted implementation of carp management yields the highest return on investment when compared to other restoration strategies.
$567,000 the second year is to the commissioner of natural resources for an agreement with the Minnehaha Creek Watershed District to restore and enhance fish habitat in the Six Mile Creek - Halsted Bay subwatershed. A list of proposed restorations and enhancements must be provided as part of the required accomplishment plan.
This habitat restoration project will have benefits across the entire trophic chain. Now that carp populations are reduced, we will continue to conduct effectiveness monitoring to assess the improvement of aquatic vegetation, macroinvertebrates, and water quality, restoring food and habitat for numerous species of fish and wildlife, and in turn, restoring populations of these species.
In particular, carp management will allow shallow lakes to shift to a new, healthier stable state. Much of the subwatershed?s littoral area currently lacks a healthy plant community. However, with fewer carp uprooting vegetation, submerged aquatic vegetation should return to littoral areas of restored lakes. Evidence suggests that this alternative stable state positively impacts the food web on many levels. Higher abundance and diversity of aquatic vegetation are related to higher abundance, diversity and growth rates of fish and waterfowl, because vegetation provides better refuge and spawning habitat. These factors, combined with reduced competition for macroinvertebrates and other food, explain why carp management can have indirect effects on many species.
The area contains over 75 species of birds including over 20 species of waterfowl that breed or migrate through the area, has over 15 Minnesota Biological Survey (MBS) Sites of Biodiversity significance, and the lakes support over 20 species of fish. These restoration benefits are endorsed by the Minnesota Waterfowl Association and the US Fish and Wildlife Service.
Specific species that will benefit include:
Harvested waterfowl: Mallard, Wood Duck, Blue and Green-winged Teal, Canada Goose, Snow Goose, American Black Duck, Northern Shoveler, Northern Pintail, Ring-necked Duck, Bufflehead, Common Goldeneye, Hooded Merganser, Common Merganser, American Coot, and Lesser Scaup.
Water-birds listed on the Minnesota DNR Species in Greatest Conservation Need (including but not limited to): Northern Pintail, American Black Duck, Lesser Scaup, Trumpeter Swan, Common Loon, Great Egret, Green Heron, Western Grebe, Horned Grebe, Red-necked Grebe, Eared Grebe, Night Heron, Franklin?s Gull, Black Tern, Forster?s Tern, Common Tern, American White Pelican, American Bittern, Semipalmated Sandpiper.
Game and non-game fish: Largemouth bass, northern pike, walleye, muskellunge, yellow perch, bluegill, pumpkinseed, shiners, Iowa darter, brook silverside, johnny darter, minnows, white sucker, and black/white crappie.
MCWD Levy, MCWD Levy and USFWS